REMOVAL OF THE AUTOMATIC - Toyota Corolla, 1.8 L, 2003

Box-machine gun: all about tuning automatic transmission

The invention of the ICE itself was not yet the invention of the automobile. It was also necessary to somehow drive the car, turn, brake. And one of the most difficult tasks was the transmission of torque from the engine shaft to the drive axle.

However, the first cars had no gearbox at all - the motor turned the drive wheel at once. But at the time, it was about walking speeds and toy powers. As soon as these values ​​increased, it became clear that the transmission was indispensable.

That is, a car, in principle, can drive without a gearbox. But, to accelerate to more or less decent speeds, you need incredible power. History knows even sports cars without a gearbox, for example, the White Triplex, which in 1928 developed a speed of 334 km / h! But its power plant was a block of three aircraft engines with a total volume of 81.2 liters and a capacity of 1,500 "horses".

Try to drive all the time in one gear - or you stall, or the engine spins into the red zone. There is no need to talk about comfort without a checkpoint.

By the way, the automatic transmission was originally intended specifically for greater driving comfort. And then she came to motorsport. With other technologies, the opposite is often the case.
From word to deed

In the company of "real boys", the attitude towards automatic transmission has developed quite unambiguously - a toy for blondes and mama's sons. We hasten to clarify. The fastest cars on this planet are dregsters of the highest classes with a quarter time of 7 seconds or less. And there is a rational explanation for this: firstly, with such an intense acceleration, there is no time to be distracted by gear shifting - he gape a little, did not correct the movement in time - and the cutlet made of metal and bones is ready. And, secondly, no matter how professional the pilot is, no matter how well he knows his car, the "automatic" will still stick the transmission more clearly and more accurately. That's why he is a machine gun.

You say - bullshit! The machine gun is stupid, and in general, it is not intended for motors stronger than 300 forces. The answer is in the title of the article. The automatic transmission is also tunable.
Educational program

Let's first figure out how it works. "Automatic", in fact, is a mechanical planetary gearbox plus a torque converter (GT, Torque Converter) consists of two vane machines - a centrifugal pump, a centripetal turbine and a guide vane-reactor located between them and, in addition to performing the clutch function, automatically changes the torque depending on the load and wheel speed. In order to reduce the size of the gas turbine and reduce losses for fluid overflow from the pump to the turbine, the latter are as close as possible, and their wheels are shaped to provide a continuous circle of working fluid circulation - everything is simple and, at the same time, effective!

Now the most interesting thing: the impeller is connected to the engine crankshaft (like the driving clutch disc in cars with manual transmission), and the turbine is connected to the gearbox shaft (like the driven disc). But there is no rigid connection, as in "mechanics", between them - the transfer of energy is carried out by flows of working fluid.

In general, a fluid coupling works according to this scheme, which transmits torque, but does not transform its value. To change the moment, a reactor was introduced - this is also a wheel with blades located on the way of returning the oil to the turbine, but the blades have a special complex profile - such that the interscapular channels gradually narrow. Thus, the speed of the working fluid increases in proportion to the speed of rotation of the crankshaft of the engine, and the fluid itself, being ejected from the reactor towards the impeller, drives it, i.e. the torque on the output shaft of the torque converter increases, and, with a constant pump operating mode, the turbine operating mode changes automatically and steplessly depending on the resistance applied to the turbine shaft.

Here is a diagram of the automatic transmission in a highly simplified form. In fact, all this trouble is controlled by a dozen more sensors, plus torsional vibration dampers, etc., etc., etc., which is aimed primarily at the comfort of switching - the absence of jerks, vibration, noise.
What to turn, where to turn

With the same power, the car in which gear changes faster accelerates faster. But how to make the "machine" that is "on its mind" work faster? The answer is simple - tuning hydraulic brakes, i.e. chip tuning. But this refinement entails many more

Faster shifts will also require more oil pressure in the GT, that is, it is necessary to chip the electronics of the automatic transmission (Electronic Pressure Control Solenoid) to supply higher transmission oil pressure (Automatic Transmission Fluid, ATF). But, as you know from the physics course, the higher the pressure, the higher the temperature. This means that an additional ATF cooler should be installed (a cooler from Pajero is popular, for example), otherwise the tuning box will not last long.

It will not be superfluous to use a reinforced pump and a torque converter turbine - otherwise there is a great chance to rip the blades! Can you imagine how monstrous the pressure is created in the GT?

In our country, automatic transmission tuning is still in its infancy, and therefore, due to the acute shortage of special GTs (with reinforced blades), experts most often offer to install a torque converter from a more powerful car (the same Pajero), and carry out further work with it.
And this is just the first step

There is one more important subtlety. For most engines, pickup starts at medium speed (about 3000-3500 rpm), while turbocharged engines have a "turbo lag" up to this limit, and pickup starts at 3500-5000 rpm. With a manual gearbox, nothing interferes with starting from the required speed, but in the "automatic" the crankshaft speed is constantly monitored by the input speed sensor (ISS) connected to the converter (Stolconverter) of the torque converter, which, like you already, probably managed to understand, and is the most important part of the "machine". Stolconverter, in turn, is responsible for another important constant in the automatic transmission settings - Stolspeed. By itself, "stolspeed" in literal translation - "fast start speed" - is incredible nonsense. In fact, this is a crankshaft speed controller, at which the car starts to move. In the "stock" version, it is usually set to 2200 rpm to reduce the load on the drivetrain. Experts, on the other hand, offer to "dig deeper" in electronics again and move the table speed by 3000 rpm or even higher.

We got stiffer shifting and axle boxes when the gas pedal is pressed to the floor. But now the load on the clutches has increased many times over.

This is also solvable: you should replace the standard clutches with special ones, which have an increased contact area of ​​the driving and driven parts. But the internal space of the automatic transmission is limited, that is, the new clutches, with an increased area, must fit into the old overall dimensions. The desired effect is achieved by using a larger number of thinner clutches, the working part of which is made of materials with increased strength characteristics - kevlar, cermets, composites.

In the end, it is worth noting that with an old, low-quality or fake ATF, all these changes do not make sense. If you want your horse to run briskly and for a long time - feed it with quality oil.
Issue price

Here is the budget for tuning the automatic transmission for Toyota Soarer`1995 hydraulic brakes
tuning - $ 700.
torque converter tuning - $ 700
reinforced clutches - 1200 USD
additional ATF cooler - $ 200
work - 1000 USD
Total: 3800 USD